The present invention relates to a device for replenishing toner to a developing device included in a copier, facsimile apparatus, printer or similar image forming apparatus in order to develop an electrophotographic image by toner.
A conventional toner replenishing device is disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 61-157962. The replenishing device includes a toner container containing fresh toner and removably mounted to an apparatus body. The toner container is formed with a slot for discharging the toner. An agitating member is disposed in the toner container and mounted on a rotary shaft in order to agitate the toner. A drive transmitting member is operatively connected to a drive source. An engaging member is also mounted on the rotary shaft and engageable with the drive transmitting member when the toner container is mounted to the apparatus body. When the toner container is mounted to the apparatus body, the engaging member is engaged with the drive transmitting member and rotated by the drive source via the drive transmitting member, thereby replenishing the toner into a developing device.
The toner replenishing device of the kind described has some problems yet to be solved, as follows. Assume that the engaging member for transferring the driving force from the drive source to the rotary shaft is affixed to the shaft at the outside of the toner container. Then, the engaging member is apt to break when, for example, the toner container is let fall by accident. Moreover, if the agitating member is rotated when the toner in the toner container is solidified, it is likely that the toner exerts an excessive load on the agitating member and breaks the shaft of the member.
In another conventional toner replenishing device, a toner container storing fresh toner is provided with a spare toner containing portion thereinside. The spare toner containing portion is mounted on a rotary shaft and feeds, while in rotation, spare toner to the container via an opening formed in the top thereof. A lug and a groove are respectively formed in the shaft and the side wall of the toner container and engaged with each other by a spring. When the lug and groove are released from each other against the action of the spring, the shaft is allowed to rotate. For this type of device, a reference may be made to Japanese Utility Model Laid-Open Publication No. 61-19257.
There has also been proposed a toner replenishing device constructed to replenish toner to a developing device while preventing it from solidifying, as taught in, for example, Japanese Utility Model Laid-Open Publication No. 60-176448. In this kind of device, toner is replenished into the developing device from a toner replenishing section. A toner containing section is communicated to the toner replenishing section in order to feed the toner. An agitating member is disposed in the toner containing section while a rotatable member is operatively connected to the agitating member by a spring. The rotatable member is connected to a drive source via an intermittent rotation mechanism.
Further, Japanese Utility Model Publication No. 53-21965, for example, discloses a toner replenishing device including a reservoir storing toner to be replenished into a developing device. A rotatable member is received in an outlet which is formed in the bottom of the reservoir. Sharp vibration is applied to the rotatable member in the axial direction of a shaft supporting the rotatable member, so that the toner in the reservoir is prevented from bridging.